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GCE JUN 2006 : (AS 1) Cell Biology

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Centre Number 71 Candidate Number ADVANCED SUBSIDIARY (AS) General Certificate of Education 2006 Biology assessing Module 1: Cell Biology ASB11 Assessment Unit AS 1 [ASB11] MONDAY 5 JUNE, MORNING TIME 1 hour. INSTRUCTIONS TO CANDIDATES Write your Centre Number and Candidate Number in the spaces provided at the top of this page. Write your answers in the spaces provided in this question paper. Answer all eight questions. You are provided with Photograph 1.3 for use with Question 3 in this paper. Do not write your answers on this photograph. For Examiner s use only Question Number 1 2 INFORMATION FOR CANDIDATES The total mark for this paper is 55. Section A carries 43 marks. Section B carries 12 marks. You should spend approximately 15 minutes on Section B. You are expected to answer Section B in continuous prose. Quality of written communication will be assessed in Section B. Figures in brackets printed down the right-hand side of pages indicate the marks awarded to each question or part question. ASB1S6 735 3 4 5 6 7 8 Total Marks Marks Section A Examiner Only Marks 1 Remark (a) Complete the following table by identifying the carbohydrates described. Role of carbohydrate in living organisms Carbohydrate Carbohydrate which forms part of the structure of RNA Form in which carbohydrate is transported in flowering plants Form in which carbohydrate is stored in animals Structural carbohydrate forming the cell walls of plants [4] (b) (i) How does the number of fatty acids found in a triglyceride differ from the number of fatty acids found in a phospholipid? ______________________________________________________ ___________________________________________________ [1] (ii) Explain how a saturated fatty acid differs in structure from an unsaturated fatty acid. ______________________________________________________ ___________________________________________________ [1] ASB1S6 735 2 [Turn over 2 The diagram below shows the phases of the cell cycle. Examiner Only Marks Remark S G2 G1 Mitosis Cytokinesis (a) During which phase in the diagram of the cell cycle do the following events occur? DNA replication ______________________________________________________ Build up of ATP ______________________________________________________ Separation of chromatids ______________________________________________________ [3] (b) Describe the process which results in the splitting of the cytoplasm (cytokinesis) in plant cells. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S6 735 3 [Turn over 3 Photograph 1.3 is an electron micrograph of a Golgi body ( 90 000). Examiner Only Marks Remark (a) Identify the two faces of the Golgi body labelled A and B. A __________________________ B __________________________ [2] (b) Describe how the Golgi body is formed in the cytoplasm. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] (c) Outline one function of lysosomes produced by the Golgi body. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S6 735 4 [Turn over BLANK PAGE (Questions continue overleaf) ASB1S5 735 5 [Turn over 4 (a) The temperature at which an enzyme and its substrate are maintained will influence the subsequent rate of reaction. The graph below shows the effect of an increase in temperature, from 5 C to 40 C, on the activity of an enzyme-controlled reaction. Examiner Only Marks Remark 100 Rate of reaction/arbitrary units 80 60 40 20 0 0 5 10 15 20 25 30 35 40 45 Temperature/ C (i) In this investigation, the enzyme and the substrate were dissolved in a buffer solution. Explain why a buffer solution was used. ______________________________________________________ ___________________________________________________ [1] (ii) Using the information in the graph above, explain the effect of a change in temperature on the rate of reaction. ______________________________________________________ ______________________________________________________ ______________________________________________________ ___________________________________________________ [2] ASB1S6 735 6 [Turn over (iii) The effect of a 10 C rise in temperature on the rate of reaction is known as its temperature quotient (Q10). It is calculated using the equation Examiner Only Marks Remark rate of reaction at 10 C above a certain temperature Q10 = rate of reaction at a certain temperature In the space below, calculate the Q10, for a temperature rise from 20 C to 30 C, for the enzyme-controlled reaction shown opposite. [2] (b) Enzymes are proteins and, at temperatures over 50 C, they are denatured and will no longer function. Explain what happens to bring this about. _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] ASB1S6 735 7 [Turn over 5 The diagram below shows a stage in the synthesis of a polypeptide. Examiner Only Marks Remark (a) Describe, precisely, what happens at the next stage in the synthesis of the polypeptide. _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [4] ASB1S6 735 8 [Turn over The table below shows a mRNA codon for each of four amino acids. Examiner Only Marks Amino acid mRNA codon Arginine AGA Cysteine UGU Serine UCU Threonine Remark ACA (b) Use the information in the table to determine the (i) DNA code for the amino acid cysteine _________________ [1] (ii) amino acid coded by the DNA code TGT _________________ [1] (iii) amino acid transferred by the tRNA with anticodon UCU _________________ [1] ASB1S6 735 9 [Turn over 6 The diagram below shows an experiment in which a Visking tubing bag (made from a selectively permeable membrane) containing undiluted seawater was immersed in a solution of 50% seawater. At the same time a marine worm, Nereis diversicolor, was placed in a solution of 50% seawater. Visking tubing bag Examiner Only Marks Remark marine worm 50% seawater undiluted seawater The mass of both the bag and the marine worm were recorded at intervals of 2 hours over a period of 12 hours and expressed as percentage increase in mass. The results are shown in the graph. 40 Percentage increase in mass/% Visking tubing bag 30 marine worm 20 10 0 0 ASB1S6 735 2 4 6 Time/hours 10 8 10 12 [Turn over (a) Explain the changes in the mass shown for the Visking tubing bag over the 12 hour period. (Your explanation should refer to the water potential of the solutions.) Examiner Only Marks Remark _________________________________________________________ _________________________________________________________ _________________________________________________________ ______________________________________________________ [2] (b) (i) Describe how the changes shown in the graph for the marine worm are different from the changes shown for the Visking tubing bag. ______________________________________________________ ______________________________________________________ ______________________________________________________ ___________________________________________________ [2] (ii) During the experiment the marine worm increased the volume of urine excreted. How might losing urine have influenced the mass changes of the marine worm? ______________________________________________________ ___________________________________________________ [1] (iii) Another adaptation of this marine worm is that it slowly reduces the salt content of its body fluids to a level closer to the salt content of the surrounding water. How would losing salt influence the water potential of the marine worm, and subsequently have influenced the mass changes of the marine worm? ______________________________________________________ ______________________________________________________ ______________________________________________________ ___________________________________________________ [2] ASB1S6 735 11 [Turn over 7 Dental decay is commonly caused by the corrosion of enamel by lactic acid-producing bacteria. Examiner Only Marks Remark A strain of the bacterium Streptococcus mutans produces a toxin which kills other bacteria. It was considered that this might be used against lactic acid-producing bacteria in the mouth, and so prevent tooth decay. However, the S. mutans strain itself produces lactic acid. Genetic engineers have discovered the genes responsible, one coding for lactic acid production, and another coding for the production of the toxin. The aim of the engineers was to remove the lactic acid gene while retaining the toxin gene. The genetic engineers considered the use of three possible enzymes, A, B and C, to remove the lactic acid gene. The table below shows the base sequences that enzymes A, B and C identify and cut. Enzyme Cutting action of enzyme A TTCAGT AAGTCA B AAATAC TTTATG C GGTTAC CCAATG (a) What type of enzymes are A, B and C? ______________________________________________________ [1] ASB1S6 735 12 [Turn over The diagrams below illustrate the base sequences found on either side of the lactic acid gene and the bacterial toxin gene. Examiner Only Marks Remark GGT TAC T T CAGT GGT TAC T T CAGT Lactic acid gene CCAATGAAGT CA CCAATGAAGT CA AAATAC T T CAGT T T TATGAAGT CA Bacterial toxin gene AAATAC T T CAGT T T TATGAAGT CA (b) Using the information in the diagrams and the table opposite complete the table below by stating the effect on the lactic acid gene and the toxin gene of treating the strain of bacteria with enzymes A, B and C. (Answer yes or no.) Enzyme used Is the lactic acid gene removed? Is the toxin gene removed? A B C [3] (c) Which of the enzymes A, B or C could be used to genetically modify the strain of bacterium to potentially eradicate tooth decay? ______________________________________________________ [1] ASB1S6 735 13 [Turn over Section B Examiner Only Marks Remark In this section you are expected to answer in continuous prose, supported, where appropriate, by diagrams. You are reminded that up to two marks in this question are awarded for the quality of written communication. [2] 8 Give an account of the structure of the cell surface membrane and its role in facilitated diffusion and active transport. [10] Structure of the cell surface membrane _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1S6 735 14 [Turn over Role in facilitated diffusion and active transport Examiner Only Marks _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ _____________________________________________________________ ASB1S6 735 15 Remark S 5/05 6700 302507(38) [Turn over GCE Biology Advanced Subsidiary (AS) Assessment Unit AS 1 Module 1: Cell Biology Summer 2006 Photograph 1.3 (for use with Question 3) A B rough endoplasmic reticulum ASB1S6 ASB11IN1

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Additional Info : Gce Biology June 2006 Assessment Unit AS 1 Module 1: Cell Biology
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